Non-volatile memory express (NVMe) and NVMe over fabrics (NVMeoF) (or NVMf in short) are new emerging technologies. NVMe is a standard that defines a register-level interface for host software to communicate with a non-volatile memory subsystem (e.g., a solid-state drive (SSD)) over a peripheral component interconnect express (PCIe) bus.
NVMeoF defines a common architecture that supports an NVMe block storage protocol over a wide range of storage networking fabrics such as Ethernet, Fibre Channel, InfiniBand, and other network fabrics. For an NVMeoF-based system, an X86-based central processing unit (CPU) on a motherboard is no longer required to move data between an initiator (e.g., host software) and a target device (i.e., an NVMeoF device) because the target device is capable of moving data by itself. The term, fabric, represents a network topology in which network nodes can pass data to each other through a variety of interconnecting protocols, ports, and switches. For example, Ethernet-attached SSDs may attach directly to a fabric, and in this case the fabric is the Ethernet.
The physical connection of the NVMe is based on a PCIe bus. A typical Ethernet SSD has a U.2 connector to interface with a system via a mid-plane over the PCIe bus. In the case of the four-lane PCIe bus (PCIe x4), the two Ethernet ports consume only two lanes of the four-lane PCIe signals, and the remaining two lanes of the PCIe X4 signals remain unused.